Duramax is king of the mountain again

spud1957 wrote:
Here's a little explanation regarding SAE certified HP.

http://www.sae.org/certifiedpower/details.htm

Are Ram's numbers bogus? They use J1995.

http://www.autoguide.com/auto-news/2015/08/are-the-2016-ram-hd-s-output-figures-bogus-.html

Did you read your second link?

Form the referenced link.
However, just because Ram uses a different procedure does not mean its claimed figures are spurious. According to SAE, the J1995 standard is:

Intended for use primarily by engine manufacturers that supply engines to other companies for installation in applications where the engine manufacturer may not control induction and exhaust system design or the speed at which the powerplant runs.

Since Ram buys its diesel engines from Cummins, this rating standard makes sense. Everything appears to be on the up-and-up.

“We were the pioneers in the large displacement turbo diesels in heavy-duty trucks,” said Cappa. Ever since Chrysler introduced the original 5.9-liter Cummins 27 years ago, he said they’ve used the same exact test procedure, J1995, so it’s not like the folks in Auburn Hills decided one morning they were going to try to game the system by using a different procedure from the rest of their competitors.

Driving his point home, Cappa noted, “Our engineers truly feel the 1995 power ratings provide a more direct reference for comparing heavy-duty engine performance.” This is because these hard-working trucks can be outfitted in countless different ways, with equipment like dual alternators, power-takeoffs and so on, all of which leads to varying parasitic losses, which Cappa said are more accurately taken into account by the J1995 standard.

Ford “We’re using 1349 for our engines,” said Mike Levine, truck communications manager at Ford, a standard they believe is more rigorous than J1995.

GM But where does General Motors, the third biggest player in the heavy-duty truck segment stand on this issue? According to Tom Read, the powertrain communications man at GM, all of their engines, unless otherwise noted, are rated using SAE J2723, a third procedure, which is arguably the most trustworthy one.

But back to test procedures. When asked if there was any estimable percentage difference between J1995 and J1349, Pollak said, “There’s so many variables, so much involved, it would be hard to make any kind of comparison like that.” Unfortunately, there’s no real way to stack them against one another.

“Each of them are equally valid, equally fine,” noted Pollak. However, “Unless you go through our certified power program … we have no oversight,” so conceivably an automaker could make nearly any claim they wanted. “And that’s one of the reasons we started our certified power program,” added Pollak.


All of that to say GM is the only one using the SAE J2723 at the time of this article on Aug 28, 2015.